This invention relates to the field of animal husbandry and particularly to a system for receiving waste material excreted by the animals, bacterially decomposing the material to produce methane gas, and separating and removing the liquid and solid products of such bacterial decomposition.
It is widely known that a product of bacterial decomposition of sewage and animal waste is methane gas. Many proposals have been made for collecting and utilizing such gas in municipal sewage systems and in conjunction with animal feed lots, dairy barns and other animal enclosures. None of these proposals has met with a significant degree of success. Although the specific reasons for prior failures are not known to the present inventor, it is believed that one of the primary problems has related to the presence of excessive liquid content and difficulties or inabilities in removing liquids and solids from chambers where the waste materials are undergoing treatment.
It is an object of this invention to provide an uncomplicated but efficient system for raising animals and handling the waste materials excreted thereby to produce methane gas.
Another object of the invention is to provide an animal enclosure system with a methane gas generator which has a satisfactory means for removing excess liquid from the material undergoing treatment, and/or for removing undigested dense solids from the chamber where the material is being treated.
A further object is to provide for pretreatment of the animal waste material in a holding tank system which permits process controls and produces ammonia gas.
Another object is to provide a complete system which utilizes available solar energy and vegetation nutrient by-products from the system.
Still another object to process animal waste material under conditions which optimize gas generation and conserve to a maximum extent all materials produced by the system.
According to one basic principle of the invention, an animal enclosure system has a platform for supporting animals and receiving their solid wastes, a gas enclosing digestion chamber for containing a mixture of the animal waste and water or other carrier liquid, means for conducting waste from the platform to the chamber, a gas outlet opening located in an upper portion of the chamber above the mixture, a conveyor for moving dense solids through the bottom of the chamber from the inlet end to the solids outlet opening, and then to a discharge point outside the chamber and above the liquid level. Liquid from within the chamber passes over an overflow means which maintains the mixture at a given liquid level. A liquid outlet passage leads downwardly from the overflow point and then upwardly to a discharge point located outside the chamber. Liquid discharged from the treatment chamber may go to an evaporation lagoon.
A plurality of holding tanks are provided for receiving the waste material from the animal platform and holding the waste material at ambient atmospheric temperatures to permit the bacterial generation of ammonia gases prior to delivery of the waste materials to the methane generation chamber which preferably is heated to promote the methane-generating bacterial activity.
Other inventive concepts are within the purview of the invention, only a typical example of which is described hereinbelow.